Method of making waterproof fiber board



Patented Apr. 3, 1934 warren s'mres 1,953,397 sm'rnon or MAKINGwarearnoor rmsa nosan Edwin J. Elmer, Monroe, Mich, asaignor to GanderFibre Products Company, Detroit, Mich, a. corporation of Michigan NoDrawing. Application June 12, 1931,

Serial No. 544,043

6 Claims. (Cl. 92-21) T This invention relates to a water-proof lami-'nated board and to a method of manufacturing same, whereby thewater-proofing material will completely permeate the body of the board,as

well as the portions forming the exposed surfaces thereof.

For many purposes it is desirable to provide fiber board or productswith moisture resistant properties so that such material or produce can10 be used in situations in which they are exposed to dampness from anycause. Wall boards, insulating boards, fiber-boards suitable for use inautomobile foundations and pyroxylin-coated panels, and like artificialboards, preferably,

should possess moisture resistant properties to a high degree. Otherproducts, not in the form of a board, but constructed of similarmaterial and subjected to the same conditions, likewise must possesssimilar water resisting properties.

Heretofore, fibrous materials, composed chiefly of vegetable fibers,such as wood pulp, asbestos fiber, or any suitable paper making materialhaving been rendered water-proof to varying degrees by one of two knownprocedures. The most commonly used method consists in impregnating thefinished fiber board with the water-proofing substance, which mayconsist of asphalt, paraffin or various resins dissolved in a suitablesolvent. The product resulting from this mode of. procedure is not verysatisfactory, due to the fact that the water-proofing materials, as arule, do not penetrate the interior of the board sufficiently forefficient water-proofing. Generally, there is only a film of thewater-proofingsubstance on the outside of the board, which film does noteffectively resist the action of moisture.

It has also been, heretofore, proposed to water-proof fibrous productsby adding to the stock, from which thefibrous material is made, an

emulsified suspension of a normally adhesive pitchy or bituminous binderin water, the normally adhesive material being maintained in suspensionby a suitable emulsifying agent. Such composition wasadded to thematerial or stock from which the fibrous products are made, so

solution have been used in the manner above This invention aims toprovide a method or process of manufacturing water-proof boards of thekind in which the entire thickness of the board is permeated by awater-proofing substance that, at one stage of the manufacture of theboard, is sufiiciently fluid so that it may flow throughout theinterstices in the board and-serve to intimately connect the fibers, aflow of the waterproofing substance in solution taking place from theinterior of the board toward the exposed surfaces thereof, rather thanby flowing the solution toward the interior of the board from theexposed surfaces, as has heretofore been the practice whenwater-proofing substances in stated.

A further object of the invention is to provide an improved process ofmanufacturing waterproof fiber board in which a normally adhesivewater-proofing substance is included only in the stock which goes, inthe completed board, to form I the central portion or body thereof, thestock forming the liner layers of the board being maintained free ofsuch adhesive water-proofing substances, so that the liner layers, whichare applied to opposite sides of the body that carries thewater-proofing substances, may serve during the passage of the materialthrough the machine, to protect the felts and rolls thereof from contactwith the adhesive substance.

Another object of the invention is to provide an improved process ofmanufacturing fiber board in which the normally adhesive water-proofingsubstance is distributed through the stock of which the board is made,while in a non-fluent condition. From this condition it may subse-'quently be converted so as to flow throughout the board when such boardis saturated with a solvent for the water-proofing substance.

This invention also aims to provide a laminated board consisting of aplurality of layers, one or more of which contains the water-proofingsubstance in a form from which it may be readily converted into awater-proofing solution of substantial fluidity to permeate the adjacentlayers of the laminated board, so as to fill the interstices in thelamination, that initially carries the water-proofing substance, as wellas the interstices of the lamination or lamlnations that are disposedadjacent thereto.

A further object of the invention is to provide a'method of making alaminated board, consisting of an intermediate layer and outer layersdisposed on opposite sides of the intermediate layer, whereby adhesivewater-proofing material, initially applied to the intermediate layer,may be utilized to combine the surface layers to the intermediate layer,by causing said adhesive material to flow from the intermediate layertoward said surface layer or layers and into the interstices therein.

A still further object of the invention is to provide a water-prooffiber board having its entire thickness thoroughly permeated by awaterproofing substance in solution, and to provide a water-proof boardin which the water-proofing substance in solution-flows from theinterior of the board toward the outer or exposed surfaces.

In practicing the present invention the usual paper making materials areused and said materials are prepared in any well known and approvedmanner. To such paper making materials the water-proofing substance isadded, preferably in the heaters. The water-proofing substance may beany natural or artificial asphalt or other residual product ofpetroleum, coal tar pitch, or other pitches, and analogous fusible,soluble pitches, or resinous substances. Asphalt, paracoumarone resin,shellac,'ester gum, gum damar, gum sandarac, gum copal, or rosin, areexamples of water-proofing substances that may be .incorporated in thepaper making materials in accordance with this invention.

If a water-proofing substance is used that is normally dry and can bepowdered in such condition, the substance is ground, in any suitablemanner so that it is in a finely divided condition. In this condition itis incorporated in the paper stock in any suitable way, so as tosubstantially uniformly distribute the particles of the waterproofingsubstance throughout the st0ck. In the event that a water-proofingsubstance is used,

\ such as certain'coal tar pitches for example, which can only be groundin cold water, the substance is reduced to a finely divided state inthis form, and the finely divided substance, in suspension in the waterin which it was ground, is added to the paper composition without firstdrying the ground product.

Having added the water-proofing substance to the paper stock, as justdescribed, said stock is prepared in the usual manner until it hasreached the condition required to form a satisfactory sheet on the papermachine.

The sheet resulting from the paper stock, prepared in the manner justdescribed, will accordingly contain the usual paper making material andchemicals and, in addition, a'water-proofing substance in finely dividedor comminuted form thoroughly distributed throughout the product. Ifdesired, suitable mineral fillers may be 'incorporated in the stock withthe water-proofing agents, such, for example, as asbestine, clay, di atomaceous silica, silica, mineral pigments, such as red oxide, theochres and umbers, chalk, magnesite and slate dust.

The paper stock including the finely divided or comminutedwater-proofing substances, which are normally adhesive and have atendency to 1 stick to the rolls and felts of the paper making machine,is, preferably, used only to form the body or central portion of thecompleted laminated board. This is accomplished by using the stock,containing the water-proofing substance distributed therethrough, toform the filler, and by using stock prepared in well known manner, butwithout water-proof substance to form liner layers. for the oppositesurfaces of the filler. Since the liner layers include no normallyadhesire substance, they serve to protect the rolls and felts fromcontact with the adhesive material included in the body of the board,thus preventing gumming up of the felts and rolls of the machine.

Accordingly, the board is preferably prepared by running the stock,containing the water-proofing substance, between liner layers of stockcontaining none of said substance, and in forming a laminated board inthis way. The product, thus produced, is pressed, dried and may be woundinto rolls in the usual manner.

The resultant board has a center or body that is fairly water-proof, butthe liners for the board are capable of absorbing a percentage ofmoisture. However, even the center or body of the board, in thisincompleted condition, is not sufficiently water-proof, because thewater-proofing elements are simply physically mixed with the stock inthe form of individual particles, and in view of the fact that saidparticles are physically separated from each other, and are notintimately united with the fiber, the board does not exhibit greatstrength, as determined by the well known Mullen test.

Its water-proofing qualities and its strength are then vastly improvedby passing the product, prepared in the manner just described, through asolvent for the water-proofing substance contained in the center or bodyof the board. The solvent selected for impregnation, in accordance withthis step of the improved process, of course,

depends upon the material to be acted upon.

Benzol or toluol are eflicient solvents for asphalt or pitch, orcombinations of these solvents with naphtha to reduce the fire hazardmay be employed. Ethyl or methyl alcohol is a suitable solvent forshellac, while ester gum is soluble in benzol, toluol, alcohol, acetone,etc.; rosin is soluble in a wide variety, of solvents such as ethylalcohol, methyl alcohol, vthe esters such as ethyl, butyl and amylacetates, benzol, acetone, toluol and turpentine, for example. Inasmuchas the solvents for the water-proofing substance as above mentioned arewell known by those skilled in the art, further examples of suitablesolvents need not be given.

The board containing the finely divided or comminuted particles ofwater-proofing substance may be passed repeatedly through the sol vent,so that it becomes saturated with said solvent, with the result that theparticles of waterproofing substance are dissolved and the solution ofthe particles spreads throughout the adjacent fiber and causes acombination of adjacent particles. At the same time, the solution ofthefinely divided particles of water-proofing substance flows from thecenter or body of the product toward the outer surfaces thereof and thusserves to seal the interstices in the liner layers of the board. Thewater-proofing substance in this way thus also serves to firmly unitethe liner layers to the filler of the'product producing. a substantiallyhomogeneous board.

If desired, in' order to further water-prooi the liner layers of thelaminated product, just described, a small percentage of a waterproofing substance may be included in the solvent prior to the passingtherethrough of the laminated product, though as will be obvious,insuflicient water-proofing substance should be included inthe solventso that the effectiveness of the solution uponthe finely dividedparticles 01' waterproofing substance within the body of the board isnot materially diminished and so that the solution has a high degree offluidity so that it able water-resisting adhesive.

necasov can penetrate the board. When this procedure is followed, theliner layers are water-proofed both by the application thereto of awatered in the body or central portion thereof, or by the solutioncombining such solvent in a small percentage of a suitablewater-proofing substance, the board is thoroughly dried, resulting in aproduct in which the individual fibers of the board are intimatelycombined and the interstices between said fibers are sealed by thewater-proofing substance, producing a board that is highly resistant tomoisture and in which the center or body of the board is at least asthor-' oughly impregnated with the water-proofing substance as theportions thereof-that are more nearly adjacent to the outer surfaces.Inasmuch as the steps necessary to produce this improved product, justdescribed, are extremely simple it is apparent that the product may bemanufactured at a relatively low cost.

Ii desired, water-proofing substances that are not in powdered form maybe included in the stock from which the filler of the board ismanufactured, though pulverulent materials arepreferred because of theease with which the small particles can be distributed throughout themass from which the filler is made. Asphaltic emulsions in watermay beincorporated in the filler of the board and subsequently the asphalticmaterial in said body may be caused to flow into the liner layers bysaturating the board with a suitable solvent for the asphaltic materialin the manner above described.

Various combinations of the board prepared in the manner fully describedmay be made to provide a board of greater thickness. For example, two ormore plies of paper board, prepared as above described and possessing ahigh degree of resistance to moisture may be combined with chip,container, kraft, celutex, chestnut or any standard paper or insulating"material by combining the sheets or layers by means of a suit- Forexample, a very good water-resisting board of eighty points can beconstructed by using two outside liner plies of board processed inaccordance with the present invention to a thickness of twenty three.points, and one ply of thirty-four points Chestessentialcharacteristics thereof. The present embodiment is therefore to beconsidered in all respects as illustrative and not restrictive, thescope ofthe invention being indicated by the appended claims rather thanby the foregoing description, and all changes which come within themeaning and range of equivalency of the claims are therefore intended tobe embraced therein. I

v What is claimed and desired to be secured by- United States LettersPatent is:

1. The process of manufacturing water-proof fiber board composed of afiller disposed between liner layers, which consists in mixing awaterproofing substance with the stock of the filler in a relativelynon-fluent form, combining said stock with the liner layers so that thelatter prevents contact of said substances with the felts or rolls, andthen saturating the product with a solvent to cause said substance toflow into the interstices in the filler and in the liner layers.

2. The process of manufacturing water-proof fiber board composed of afiller disposed between liner layers, which consists in applying asoluble Water-proofing substance to the filler while main--v tainingsaid liner layers free of said substance during the formation of theboard, and then saturating the board with a solvent to cause saidsubstance to flow from the filler toward the exposed surfaces of saidliner layers.

3. The process of manufacturing water-proof fiber board composed of afiller disposed between liner layers, which consists in mixing anormally adhesive water-proofing substance in pulverulent form with thestock of the filler, combining said stool: with liner layers so as toprevent contact of said substance with the felts or rolls, and thensaturating the product with a solvent to cause said substance todissolve and flow into the interstices in the filler and in .the linerlayers.

4. The process of manufacturing water-proof 1 fiber board composed of afiller disposed between liner layers, which consists in applying apulverulent water-proof substance to the filler while maintaining saidliner layers free of said substance during the formation of the board,and

then saturating the board with a solvent to cause said substance to flowfrom the filler toward the exposed surfaces of said liner layers.

5. The process of water-proofing laminated fiber. board which consistsin including in the stock from which one or more laminations of theboard is made a water-proofing substance in nonfiuent form, combininganother lamination with said first named lamination and then saturatingthe laminated product with a solvent to cause the substance to spreadthrough the board.

6. The process of water-proofing laminated fiber board which consists inincluding in the stock from which one or more laminations of the boardis made a water-proofing substance in pulverulent form dispersedthroughout said lamination, combining other laminations with said firstnamed laimnation and then saturating the lamihated product with asolvent for said substance the laminations.

I EDWIN J.

